Title :
The oxidation of a Nd-Fe-B permanent magnet at 400°C: a SEM, microhardness and Mossbauer study
Author :
Le Breton, Jean-Marie ; Teillet, Jacques ; McGuiness, Paul J. ; Edgley, Donald S. ; Harris, Roy
Author_Institution :
Lab. de Magnetisme et Applications, CNRS, Mont-Saint-Aignan, France
fDate :
9/1/1992 12:00:00 AM
Abstract :
Nd16Fe76B8 sintered magnets were heated in an open furnace for times up to 29 days. The results of scanning electron microscope (SEM) observations, quantitative EDX/WDX analysis, microhardness measurements and Mossbauer spectroscopy were found to be consistent with the Nd2Fe14B phase having been disproportionated by oxygen entering via the surface or the cracks. The diffusion front between the oxidized region (oxygen amount~35 at.%) and the unaffected region was observed moving through the grains, indicating that at 400°C the corrosion behavior of the Nd2Fe14B phase is not intergranular in nature. This indicates that the corrosion resistance of Nd-Fe-B magnets at elevated temperatures could be enhanced by the presence of precipitates in the matrix
Keywords :
Mossbauer effect; X-ray chemical analysis; boron alloys; corrosion; ferromagnetic properties of substances; hardness; iron alloys; neodymium alloys; oxidation; permanent magnets; scanning electron microscope examination of materials; 400 degC; Mossbauer spectroscopy; Nd16Fe76B8 sintered magnets; Nd2Fe14B phase disproportionation; SEM; corrosion behavior; corrosion resistance; diffusion front; microhardness; open furnace; oxidation; permanent magnet; precipitates; quantitative EDX/WDX analysis; Corrosion; Furnaces; Iron; Magnetic analysis; Neodymium; Oxidation; Permanent magnets; Phase measurement; Scanning electron microscopy; Spectroscopy;
Journal_Title :
Magnetics, IEEE Transactions on
